Oficina MRS Honda Sevenfifty Café Racer

The Oficina MRS Honda CB750 cafe racer is a more than year-long commission by Portuguese builder Mario of Oficina MRS, transforming a Honda CB Seven Fifty RC42 into a technically extraordinary machine with bespoke carbon and Kevlar bodywork, a handmade titanium exhaust, custom radial-brake spoke wheels, and Ohlins suspension at both ends.

The Concept

Mario at Oficina MRS approaches a build the way a watchmaker approaches a movement: nothing is accepted as it came from the factory if it can be improved. The Honda CB Seven Fifty RC42 was chosen as a platform for its 750cc inline-four engine and its proportions, which suit the cafe racer silhouette Mario had in mind. Over more than a year of work, the bike was disassembled to its core and rebuilt with components that either did not exist on the market or were fabricated from scratch when they did not meet his standard.

The Build

The fuel tank is a bespoke Kevlar and carbon fibre unit with a Monza-style cap, clear-coated to expose the weave beneath. Mario sourced the leather for the single-seater saddle himself and had it hand-stitched to his specification. The front fender is leather as well, made to measure. When radial-brake spoke wheels did not exist on the market at the time of the build, Mario engineered his own: Grimeca hubs laced to Excel rims in a 3.50x17 front and 5.50x17 rear specification, with Brembo brake discs and a radial caliper arrangement that required custom fabrication. The exhaust is a titanium system by Asahina Racing, the Japanese specialist, with each section shaped for the specific geometry of this build. Front suspension uses Showa 43mm BPF forks. The rear is a custom Ohlins unit. Carburetion is handled by a custom-made Keihin CR 35mm unit with an Active ST13 oil cooler. The oscillating arm was modified with an integrated oil recuperator.

Performance

The 750cc four-cylinder engine breathes through the Keihin CR carburettor and exhausts through the Asahina Racing titanium system, with top speed reaching 240 km/h. The Showa BPF forks and bespoke Ohlins rear shock provide a suspension package that exceeds the original specification in both adjustability and response. The custom radial-brake spoke wheels reduce unsprung weight while the Brembo disc and caliper setup delivers braking performance consistent with the rest of the machine. Renthal handlebars and Spice controls complete the rider interface. Every component serves the same brief: better looking and better performing than what it replaced.

Specifications

• Builder: Oficina MRS
• Base: Honda CB Seven Fifty RC42
• Style: Cafe racer
• Engine: 750cc inline 4-cylinder
• Carburetor: Custom Keihin CR 35mm
• Oil cooler: Active ST13
• Exhaust: Titanium, Asahina Racing
• Front suspension: Showa 43/25mm BPF forks
• Rear suspension: Bespoke Ohlins shock
• Front wheel: 3.50x17, Grimeca hub, Excel rim
• Rear wheel: 5.50x17, Grimeca hub, Excel rim
• Tyres: Michelin
• Brakes: Brembo discs, custom radial spoke caliper setup
• Tank: Bespoke Kevlar/carbon, Monza cap, clear-coated
• Seat: Single-seater, hand-stitched leather
• Handlebar: Renthal
• Controls: Spice
• Max speed: 240 km/h
• Colour: Clear-coated carbon

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